A brushless excitation load-reduced vertical synchronous motor with disc spring floating excitation machine stator

Abstract

The application provides a brushless excitation load-reducing vertical synchronous motor with a disc spring floating exciter stator, and belongs to the technical field of vertical synchronous motors. The problems of large load of a thrust bearing, unreliable excitation system, split excitation and load reduction functions, only power generation function of an exciter, and complex active control of the prior art are solved. The brushless excitation load-reducing vertical synchronous motor comprises a thrust bearing assembly, a bearing box, a thrust head, an exciter rotor, an exciter stator, an elastic assembly, a top cover and a rectifier disc. The thrust bearing assembly is installed at the bottom of the bearing box, the main shaft of a main motor is installed in the middle of the bearing box, the thrust head is installed on the outer side of the main shaft of the main motor, the exciter rotor is installed on the outer side of the thrust head, the exciter stator is installed above the exciter rotor, the upper end of the exciter stator is connected with the elastic assembly, and the rectifier disc is installed on the top of the thrust head. The brushless excitation load-reducing vertical synchronous motor is mainly used for driving motors of heavy loads, large axial forces and continuous operation conditions, such as vertical water pumps, vertical water turbines and vertical axial flow pumps.

Description

Technical Field

[0001] This invention belongs to the field of vertical synchronous motor technology, and in particular relates to a brushless excitation unloading vertical synchronous motor with a disc spring floating exciter stator. Background Technology

[0002] Vertical synchronous motors are widely used in large-scale pumping stations and water conservancy projects due to their high power density and stable operation. However, the excitation system of traditional vertical synchronous motors often adopts a static excitation + slip ring brush or independent rotating exciter structure, which has the following technical defects: 1. Thrust bearings operate under heavy loads for extended periods, resulting in short lifespans and high failure rates. The vertical motor rotor's self-weight, the medium's axial force, and the combined load of the water pump are all borne by the thrust bearing. Under heavy load conditions, the bearing temperature is high, friction loss is large, and lubrication conditions deteriorate, making it prone to failures such as bearing burnout, wear, and excessive vibration. This results in high maintenance costs and significant downtime losses.

[0003] 2. Traditional excitation systems rely on slip ring brushes, which have poor reliability and require frequent maintenance. Conventional synchronous motors use a slip ring + brush structure for rotor excitation, which has problems such as brush wear, dust pollution, and arcing discharge. They are not suitable for explosion-proof, humid, dusty, or corrosive environments, and require regular brush replacement, which cannot meet the requirements for long-term maintenance-free operation.

[0004] 3. The excitation and load reduction functions are independent of each other, resulting in structural redundancy and an inability to coordinate them: Existing brushless exciters can only provide excitation power and do not have axial force compensation and load reduction capabilities; simple axial load reduction devices can only offset part of the axial force and do not have excitation function. Setting up two systems independently will increase the axial dimension of the motor, increase the difficulty of processing and assembly, and increase the manufacturing cost.

[0005] 4. Traditional exciters are rigidly fixed with radial flux structure, fixed air gap, and lack load reduction capability: Traditional vertical synchronous motors are typically equipped with brushless exciters that use a radial flux structure. The stator and rotor are rigidly mounted and the air gap is fixed and cannot be adjusted. This type of structure can only achieve the excitation power supply function and cannot generate effective axial magnetic pull. It does not have the ability to reduce the load of the thrust bearing. If the air gap is uneven, it will also cause uneven magnetic pull, which will increase the load on the motor guide bearing.

[0006] 5. Active air gap adjustment has a complex structure and low reliability, making it unsuitable for long-term continuous operation. Some adjustable air gap solutions require the configuration of sensors, controllers, electric actuators or hydraulic actuators, which are complex in structure, have many failure points and poor vibration resistance, and cannot meet the reliability requirements of long-term continuous operation in industrial sites.

[0007] 6. Lack of safety limit protection poses a risk of stator and rotor engagement and rotor rubbing. Without a mechanical limit structure, excessive magnetic pull can cause direct contact between the exciter's stator and rotor, rubbing against the rotor, and wear on the iron core, which can lead to motor failure in severe cases. Summary of the Invention

[0008] In view of this, the present invention aims to propose a brushless excitation load reduction vertical synchronous motor with a disc spring floating exciter stator, in order to solve the problems of large thrust bearing load, unreliable excitation system, separation of excitation and load reduction functions, exciter only having power generation function, and complex active control in existing vertical motors.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: a brushless excitation load-reducing vertical synchronous motor with a disc spring floating exciter stator, the synchronous motor being connected to a water pump for driving the water pump, the synchronous motor including a thrust bearing assembly, a bearing housing, a main motor shaft, a thrust head, an exciter rotor, an exciter stator, an elastic assembly, a top cover, and a rectifier disk. The thrust bearing assembly is installed at the bottom of the bearing housing, the main motor shaft is installed in the middle of the bearing housing, the thrust head is installed on the outside of the main motor shaft, the exciter rotor is installed on the outside of the thrust head, the exciter stator is installed above the exciter rotor with an initial air gap reserved between them, the upper end of the exciter stator is connected to the elastic assembly, the elastic assembly has a disc spring assembly inside, the top of the elastic assembly is connected to the top cover, and the rectifier disk is installed on the top of the thrust head.

[0010] Furthermore, the disc spring assembly includes a disc spring seat, a disc spring, and a disc spring stud, wherein the disc spring stud is connected to the disc spring seat, and the disc spring is installed in the gap between the disc spring stud and the disc spring seat.

[0011] Furthermore, the disc springs are provided in two sets, with the two sets of disc springs connected in reverse series. Each set includes four disc springs, and the four disc springs in each set are stacked and connected together.

[0012] Furthermore, the permissible compression of the disc spring is 3 mm.

[0013] Furthermore, the initial air gap between the exciter rotor and the exciter stator is 3.5 mm.

[0014] Furthermore, a guide bearing assembly is provided on the outer side of the thrust head, and the outer side of the guide bearing assembly is connected to the bearing housing.

[0015] Furthermore, the exciter rotor is connected to the thrust head via a double pigeon tail key.

[0016] Furthermore, the exciter stator is connected to a flexible assembly via a threaded double dovetail key.

[0017] Furthermore, the main motor spindle is connected to the thrust head via a key, and a split-type clamping plate is provided on the outer side of the connection between the main motor spindle and the top of the thrust head.

[0018] Furthermore, both the exciter rotor and the exciter stator are made of silicon steel sheets stacked together. The exciter rotor is equipped with a three-phase concentrated winding, the exciter stator is equipped with a three-phase distributed winding, and the rectifier disk has a built-in three-phase full-bridge rectifier module.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention utilizes the axial magnetic pull force generated by the electromagnetic coupling of the exciter stator and rotor assembly. This pull force is directed upward, forming an upward lifting force on the thrust head, which directly counteracts the downward axial force of the thrust head. Under rated load, the load reduction ratio reaches 20%~30%, and under overload conditions, the load reduction ratio increases to 50%~60%.

[0020] 2. This invention uses a rotating rectifier disk to achieve brushless excitation. The AC power output from the exciter rotor is directly converted into DC power by the three-phase full-bridge rectifier module built into the rectifier disk and supplied to the main motor rotor winding. This avoids problems such as carbon dust pollution, brush wear, and spark risk, and significantly reduces the failure rate of the excitation system. It is especially suitable for humid and dusty water pump station environments.

[0021] 3. The disc spring assembly within the elastic assembly of this invention, in conjunction with the initial air gap, forms a passive positive feedback adjustment mechanism. When the load on the water pump driven by the motor increases, the stator current of the main motor rises, the axial load on the thrust bearing increases, and the excitation current required by the main motor increases. At this time, increasing the power supply voltage of the exciter stator strengthens the magnetic pull between the exciter stator and rotor, overcoming the elastic force of the disc spring in the elastic assembly, causing the exciter stator to move downward as a whole, and reducing the air gap. The reduction in air gap further causes the magnetic pull to increase sharply according to a square relationship, significantly enhancing the lifting force and greatly improving the load reduction effect, forming an adaptive positive feedback mechanism of: increased excitation demand → increased attraction → reduced air gap → further amplification of attraction → enhanced load reduction.

[0022] 4. The maximum allowable compression of the disc spring of this invention is 3mm, which is less than the initial air gap of 3.5mm. When the disc spring is fully compressed, a safety air gap of 0.5mm is still maintained between the exciter stator and the exciter rotor, forming a mechanical hard limit, completely eliminating the risk of stator and rotor contact rubbing, and ensuring the safe operation of the motor.

[0023] 5. In this invention, the exciter rotor, exciter stator, flexible assembly, and rectifier disk are all installed in the axial space above the thrust head, without changing the main structure of the original stator, rotor, and frame of the main motor. For in-service vertical synchronous motors, only the original excitation device needs to be removed and replaced with the floating exciter module of this invention to complete the modification.

[0024] 6. The exciter rotor of this invention is connected to the thrust head via a double dovetail key with a fit tolerance of ≤0.02mm. It simultaneously achieves circumferential torque transmission and radial centering, and is vibration-resistant and anti-loosening. The exciter stator is connected to the elastic assembly via a threaded double dovetail key. The initial air gap can be steplessly adjusted by turning the thread depth, with an adjustment accuracy of ±0.05mm, ensuring consistent electromagnetic performance. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the installation of a brushless excitation load-reducing vertical synchronous motor with a disc spring floating exciter stator and a water pump according to the present invention. Figure 2 This is a cross-sectional view of a brushless excitation unloading vertical synchronous motor with a disc spring floating exciter stator according to the present invention. Figure 3 This is a cross-sectional view of the elastic assembly described in this invention; Figure 4 This is a schematic diagram of the installation of the flexible assembly described in this invention; Figure 5 This is a schematic diagram of the connection of the double pigeon tail key described in this invention.

[0026] In the picture: 1-Thrust bearing assembly, 2-Guide bearing assembly, 3-Bearing housing, 4-Main motor spindle, 5-Thrust head, 6-Double pigeon tail key, 7-Exciter rotor, 8-Exciter stator, 9-Threaded double pigeon tail key, 10-Elastic assembly, 10-1: Disc spring seat, 10-2: Disc spring, 10-3: Disc spring stud, 11-Top cover, 12-Rectifier plate, 13-Split type clamping plate, 14-Water pump. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0028] Detailed Implementation Method 1: See Figure 1-5This embodiment describes a brushless excitation-load-reducing vertical synchronous motor with a disc spring floating exciter stator. It includes a thrust bearing assembly 1, a bearing housing 3, a main motor shaft 4, a thrust head 5, an exciter rotor 7, an exciter stator 8, a flexible assembly 10, a top cover 11, and a rectifier disk 12. The thrust bearing assembly 1 adopts a tilting pad structure and is installed at the bottom of the bearing housing 3, bearing the rotor's own weight, the water pump's hydraulic axial force, and the electromagnetic axial force. The main motor shaft 4 is a hollow stepped shaft, supported by a bearing in the middle of the bearing housing 3, and its lower end is connected to the water pump impeller. Next, the thrust head 5 is sleeved on the outside of the main motor shaft 4, and transmits torque through a flat key. The top is axially fixed by a split clamping plate 13. The exciter rotor 7 is fixed on the outside of the thrust head 5 by a double dovetail key 6 and rotates synchronously with the thrust head 5. The exciter stator 8 is located directly above the exciter rotor 7, with an initial air gap of 3.5mm reserved between the two. The lower end of the elastic assembly 10 is connected to the exciter stator 8, and a disc spring assembly is set inside. The top is fixed to the top cover 11. The rectifier disk 12 is installed on the top of the thrust head 5 and rotates with the thrust head 5. It has a built-in three-phase full-bridge rectifier module.

[0029] Furthermore, the disc spring assembly includes a disc spring seat 10-1, a disc spring 10-2, and a disc spring stud 10-3. The disc spring seat 10-1 is a ring-shaped steel structure, with its bottom connected to the upper end face of the exciter stator 8. The disc spring stud 10-3 is a stepped shaft with external threads, with its lower end connected to the central threaded hole of the disc spring seat 10-1. The disc spring 10-2 is sleeved on the outside of the disc spring stud 10-3 and is located in the gap between the disc spring seat 10-1 and the top cover 11.

[0030] Furthermore, the disc springs 10-2 are provided in two sets, with the two sets of disc springs 10-2 connected in reverse series. Each set includes four disc springs 10-2, and the four disc springs 10-2 in each set are stacked and connected to ensure stable elastic force within a compression range of 3mm, adapting to the floating stroke requirements of the exciter stator 8. The maximum allowable compression of the disc springs 10-2 is 3mm, that is, when the exciter stator 8 moves downward under magnetic pull, the disc springs 10-2 are compressed by a maximum of 3mm. At this time, the disc springs 10-2 reach their maximum elastic force, limiting the exciter stator 8 from moving further downward, forming a mechanical hard limit. The initial air gap between the exciter rotor 7 and the exciter stator 8 is set to 3.5mm, which is greater than the allowable compression of the disc springs 10-2 by 3mm, ensuring that a safety air gap of 0.5mm is still maintained when the disc springs are fully compressed, avoiding contact between the stator and rotor.

[0031] Furthermore, a guide bearing assembly 2 is provided on the outer side of the thrust head 5. The outer ring of the guide bearing assembly 2 is fixed to the inner wall of the bearing housing 3, and the inner ring is fitted with the outer circle of the thrust head 5 to limit the radial sway of the thrust head 5 and improve the rotor's running stability.

[0032] Furthermore, the exciter rotor 7 is connected to the thrust head 5 via a double dovetail key 6. The double dovetail key 6 is a symmetrical double key structure, which is embedded in the double dovetail groove on the outer circle of the thrust head 5 and the double dovetail groove on the inner circle of the exciter rotor 7. It simultaneously transmits circumferential torque and radial centering, with a fit tolerance of ≤0.02mm to prevent loosening during high-speed rotation.

[0033] Furthermore, the exciter stator 8 is connected to the elastic assembly 10 via a threaded double dovetail key 9: one end of the threaded double dovetail key 9 has a double dovetail structure and is embedded in the groove at the upper end of the exciter stator 8; the other end has an external thread structure and is screwed into the threaded hole of the elastic assembly 10. By adjusting the screwing depth of the threaded double dovetail key 9, the initial air gap between the exciter stator and rotor can be steplessly adjusted with an adjustment accuracy of ±0.05mm.

[0034] Furthermore, the main motor spindle 4 and the thrust head 5 are connected by a flat key to transmit torque. A split-type clamping plate 13 is provided on the outer side of the connection part at the top of the two. The split-type clamping plate 13 consists of two semi-circular clamping blocks, which are fixed to the top of the thrust head 5 by bolts to transmit the axial force of the main motor spindle 4 to the thrust head 5.

[0035] Furthermore, both the exciter rotor 7 and the exciter stator 8 are made of silicon steel sheets laminated together to reduce iron loss. The exciter rotor 7 is equipped with a three-phase concentrated winding with fewer turns and lower inductance, making it suitable for high-frequency excitation. The exciter stator 8 is equipped with a three-phase distributed winding with lower harmonics and higher efficiency. The rectifier disk 12 has a built-in three-phase full-bridge rectifier module that uses diode rectification to convert the three-phase AC power output from the exciter rotor into DC power, which is directly supplied to the main motor rotor excitation winding.

[0036] During operation, a three-phase alternating current with a constant frequency and adjustable voltage is supplied to the exciter stator 8, forming a rotating magnetic field in the air gap. Through electromagnetic induction, a three-phase alternating current is generated in the three-phase windings of the exciter rotor 7. The three-phase current is input to the rectifier disk 12 via a cable and converted into direct current through the internal full-bridge rectifier circuit to provide excitation for the main motor rotor, realizing the synchronous motor frequency conversion synchronous start-up and stable operation.

[0037] When the exciter stator 8 and the exciter rotor 7 are electromagnetically coupled, a stable axial magnetic pull will be generated. This pull is directed upwards and forms an upward lifting force on the thrust head 5, which offsets part of the rotor's self-weight and the load's axial force, thereby reducing the effective load acting on the thrust bearing assembly 1 and achieving a load reduction effect.

[0038] When the load on the water pump 14 driven by the motor increases, the stator current of the main motor rises, the axial load on the thrust bearing increases, and the excitation current required by the main motor increases. At this time, the supply voltage of the exciter stator 8 is increased, the magnetic pull between the exciter stator and rotor is strengthened, overcoming the elastic force of the disc spring in the elastic assembly 10, causing the exciter stator 8 to move downward as a whole, and the air gap is reduced. The reduction of the air gap further causes the magnetic pull to increase sharply according to the square relationship, the lifting force is significantly enhanced, and the load reduction effect is greatly improved, forming an adaptive positive feedback mechanism of: increased excitation demand → increased attraction force → reduced air gap → further amplification of attraction force → enhanced load reduction.

[0039] When the load is too large or the magnetic pull is too strong, the disc spring 10-2 is compressed to the limit position, the exciter stator 8 no longer moves downward, the air gap remains at the minimum value, and the magnetic pull is limited to a safe range. There is no risk of the attraction force increasing indefinitely, the rotor being lifted excessively, the bearing being unloaded, or the stator and rotor rubbing together.

[0040] The specific embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific embodiments described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A brushless excitation unloading vertical synchronous motor with a disc spring floating exciter stator, wherein the synchronous motor is connected to a water pump (14) for driving the water pump (14), characterized in that: The synchronous motor includes a thrust bearing assembly (1), a bearing housing (3), a main motor shaft (4), a thrust head (5), an exciter rotor (7), an exciter stator (8), an elastic assembly (10), a top cover (11), and a rectifier disk (12). The thrust bearing assembly (1) is installed at the bottom of the bearing housing (3). The main motor shaft (4) is installed in the middle of the bearing housing (3). The thrust head (5) is installed on the outside of the main motor shaft (4). The exciter rotor (7) is installed on the outside of the thrust head (5). The exciter stator (8) is installed above the exciter rotor (7) with an initial air gap reserved between them. The upper end of the exciter stator (8) is connected to the elastic assembly (10). The elastic assembly (10) is equipped with a disc spring assembly inside. The top of the elastic assembly (10) is connected to the top cover (11). The rectifier disk (12) is installed on the top of the thrust head (5).

2. The brushless excitation unloading vertical synchronous motor with disc spring floating exciter stator according to claim 1, characterized in that: The disc spring assembly includes a disc spring seat (10-1), a disc spring (10-2), and a disc spring stud (10-3). The disc spring stud (10-3) is connected to the disc spring seat (10-1), and the disc spring (10-2) is installed in the gap between the disc spring stud (10-3) and the disc spring seat (10-1).

3. A brushless excitation unloading vertical synchronous motor with a disc spring floating exciter stator according to claim 2, characterized in that: The disc spring (10-2) is provided in two sets, and the two sets of disc springs (10-2) are connected in reverse series. Each set includes 4 disc springs (10-2), and the 4 disc springs (10-2) in each set are stacked and connected together.

4. A brushless excitation unloading vertical synchronous motor with a disc spring floating exciter stator according to claim 3, characterized in that: The allowable compression of the disc spring (10-2) is 3 mm.

5. A brushless excitation unloading vertical synchronous motor with a disc spring floating exciter stator according to claim 1, characterized in that: The initial air gap between the exciter rotor (7) and the exciter stator (8) is 3.5 mm.

6. A brushless excitation unloading vertical synchronous motor with a disc spring floating exciter stator according to claim 1, characterized in that: The thrust head (5) is provided with a guide bearing assembly (2) on the outside, and the guide bearing assembly (2) is connected to the bearing housing (3) on the outside.

7. A brushless excitation unloading vertical synchronous motor with a disc spring floating exciter stator according to claim 1, characterized in that: The exciter rotor (7) is connected to the thrust head (5) via a double pigeon tail key (6).

8. A brushless excitation unloading vertical synchronous motor with a disc spring floating exciter stator according to claim 1, characterized in that: The exciter stator (8) is connected to the elastic assembly (10) via a threaded double dovetail key (9).

9. A brushless excitation unloading vertical synchronous motor with a disc spring floating exciter stator according to claim 1, characterized in that: The main motor spindle (4) and the thrust head (5) are connected by a flat key, and a split-type clamping plate (13) is provided on the outer side of the connection part at the top of the main motor spindle (4) and the thrust head (5).

10. A brushless excitation unloading vertical synchronous motor with a disc spring floating exciter stator according to claim 1, characterized in that: The exciter rotor (7) and exciter stator (8) are both made of silicon steel sheets stacked together. The exciter rotor (7) is equipped with a three-phase concentrated winding, and the exciter stator (8) is equipped with a three-phase distributed winding. The rectifier disk (12) has a built-in three-phase full-bridge rectifier module.

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